1. Field of the Invention
The present invention relates generally to child safety restraints, and relates more particularly to child safety restraints in the form of a seat belt with a wide range of adjustability.
2. Description of Related Art
Seat belts have been used for child restraints in a number of situations, such as strollers, high chairs and shopping carts. A number of different configurations for child restraints that involve seat belts are available, and usually include some form of adjustment to permit the seat belt to be adapted to the size of the child. Most seatbelt type restraints are configured to have an attachment point to secure the seat belt to the seat structure, and a clasping point that is fitted with a cooperative clasping mechanism to secure the seatbelt about the child. Typically, the clasping point is secured or released to restrain or free the child respectively.
Straps typically supplied with a child restraint seat belt are often made to be adjustable to provide a tailored fit for the child in the child seat. Strap adjustments are made to fit the child into the strap harness or seat belt to properly restrain the child and allow for different size children, or the growth of the child over an extended time interval. In the case of publicly available or commercial child seats, such as can be found in high chairs in restaurants or shopping cart seats for a child, the child restraint seat belt operates to restrain children with a wide variety of sizes and shapes. That is, the seat belt restraint is called upon to restrain infants in the range of several months of age, weighing approximately 15 pounds, up to or beyond children of about four years or 48 months of age, with a weight of approximately 35 pounds or more. This wide variety of ages, weights and sizes for the occupants of the child seats creates a number of challenges in properly and safely restraining the child occupant.
In the case of a typical seat belt restraint, the restraint is composed of two straps, each with a fixed end and a clasp end. The fixed ends are attached to the child seat, such as the fold out back portion of a child shopping cart seat, and the clasp ends are coupled together around the child to secure the child in place. An adjustment is provided, typically on one of the straps, to permit the size of the seat belt to be adjusted to that of the child. The adjustment is usually provided on the strap in the form of a threaded cleat to form a loop, the size of which can be changed to provide a corresponding change in the apparent or practical length of the strap. The loop typically includes either a clasp or fixed point, through which the strap can slide to permit the loop adjustment. Two different configurations of this type of seat belt restraint are illustrated in FIGS. 1A and 1B. In FIG. 1A the loop is arranged to encircle a seat fixture such as a wire 19, and another end is attached to a piece of a buckle clasp. In FIG. 1B, one end of the seat belt restraint is attached to wire 19, while the loop of the restraint encircles an attachment portion of the buckle clasp. Alternately, or in addition, one of the seat belt restraint may be attached to a fastener which is attached to wire 19. In either case of FIG. 1A or 1B, the length of the seat belt portion is adjusted by sliding the seat belt through an adjustment cleat 18 to make the loop smaller or larger and consequently make the practical length of the seat belt longer or shorter. In each case, an end of the seat belt is also attached to adjustment cleat 18.
This adjustment configuration permits a range of adjustment from nearly one-half the length of the strap to nearly the full length of the strap. However, it is not feasible to make the practical length of the seat belt portion shorter than approximately half the length of the strap, even when adjustment cleat 18 is positioned as close as possible to the fixed end of the strap without having a loose end. This limitation on how small the length of the strap can be adjusted represents a drawback in child restraint applications where attachment points may be limited. Furthermore, when the seat belt is designed to be adjusted small enough to securely restrain children in the lower end of the size range, the size adjustment configuration does not permit children to be secured in the upper end of the size range. That is, the range of adjustment of the belt configuration does not cover the range of sizes for children that are apt to be placed in the child seat, and in need of restraint.
Another belt adjustment configuration is illustrated in FIG. 1C. The belt configuration in FIG. 1C provides an adjustment for the apparent belt length by adjusting the strap through a retainer that is part of the buckle clasp piece. According to this configuration, a wide range of belt adjustment is available, simply dependent upon the length of the strap. The seat belt can be adjusted so that the buckle clasp piece is positioned very closely to rod 19, or so that the buckle clasp piece can extend approximately half the length of the strap from rod 19. However, the configuration illustrated in FIG. 1C has the drawback that it is difficult to secure the strap in the retainer in a fixed position, meaning that it is fairly easy for a child to loosen the seatbelt. In addition, the configuration shown in FIG. 1C can be dangerous when used on equipment with small children. The bigger loop determined by the longer strap represents a strangulation hazard for small children in the age range of approximately six months to one year.
If an adjustment mechanism is provided that better secures the strap, it tends to be somewhat difficult for a user to adjust due to the additional effort that is undertaken to loosen the securing mechanism to permit the strap to be adjusted to a desired seat belt length. For example, FIG. 1D shows a seat restraint where the strap is threaded through the buckle and through a cleat, leaving a loose end. The adjustment can be more difficult because the cleat is free to move the length of the strap. Also, when the restraint is adjusted to move the cleat closer to the buckle or fastener, it can be more difficult to adjust the restraint. When the cleat is in close proximity to the fastener or the buckle it is difficult to easily access the cleat or the small, tightened portion of the strap near the fastener or buckle to adjust the restraint.
Another criteria for seat belt restraints is related to compliance with standards set forth in consumer safety recommendations. The criteria in some of these standards involves specifications for the safety of children. Referring to FIG. 2, a seat belt restraint with a test dummy 22 is shown. The test dummy is seated and the seat belt restraint is secured around the test dummy. The seat belt in this instance is secured to two wire loops 25, 26 which are located on either side of test dummy 22. In this arrangement, some small gaps or play may exist in the area between test dummy 22 and shopping cart seat 24, as defined by the seat belt. Where these gaps may exist, it is sometimes possible for a child to insert an arm into the gap or to move their body laterally on seat 24, especially if the seatbelt is not adjusted properly. By being able to move their body laterally, the child may be more able to free their legs from the passive crotch restraint provided through the arrangement of wire loop 28. Any of these circumstances may result in a dangerous condition where the child may be able to free themselves from the restraint, or work the seat belt into a position closer to their neck.
Referring FIG. 3, another recommended standard test for proper seat belt restraint fit is illustrated with a test cylinder 32. A size of test cylinder 32 is representative of a child exceeding the recommended age and weight range for the child seat. For example, the cylinder can represent a child in the age range of 3½-4½ years with a weight of approximately 43 pounds. Test cylinder 32 provides test dimensions and specifications for seat belt restraints to meet a more restrictive standard where the seat belt should completely encircle the five-inch cylinder. The more restrictive standard involving the use of test cylinder 32 implies that seat belt designs should be easy for the user to adjust to a desired dimension, and should not be easily manipulated by a child. The desired dimension for the seat belt adjustment should cover the entire range of dimensions for a child that may reasonably be placed in the child seat. With the same seat belt configuration as illustrated in FIG. 2, the gaps between test cylinder 32, the seat belt and the back of the child seat becomes more pronounced. Accordingly, the use of test cylinder 32 is designed to provide a focus for child safety restraints to address the concerns discussed above with respect to FIG. 2.